1. Field of the Invention
The invention is directed to an apparatus and method for making a sheet material and, more particularly, to a sheet of material which is made into floor tile.
2. Description of the Prior Art
It is old in the flooring art to make floor tile by forming a sheet material on a mill which is a pair of consolidation rolls. The vinyl sheet material is stripped off the rolls and cooled by passing the sheet material through a water bath. The sheet material then, after cooling, is passed down to a conventional punch press structure which stamps individual 12 .times. 12 inch tiles from the sheet material. Tile normally formed in this manner is formed with tension stresses therein. That is, during the cooling of the vinyl sheet, it was subject to tension along the direction of sheet travel. When the vinyl sheet is cooled, the stresses in the sheet due to the tension on the sheet are set in the sheet. When the sheet is cut into small individual tile units, the mass of the sheet is not sufficient to prevent the sheet from shrinking in the along-machine-direction as the stresses relax. The only way the tension stresses are relaxed in the sheet is for the sheet to shrink in its along-machine-direction of processing. This results in a tile which is unstable and when these tiles are placed on a flooring, the changing of the size of the tiles causes the development of gaps between individual tiles.
U.S. Pat. No. 2,973,770 discloses that it is old to use a water slide for sliding a piece of material down into a water bath. Therein the gravity action on the piece of material is permitted to carry it down the water slide and then into the water bath. The material is then pulled out of the water bath in a cool state. Herein there is no particular consideration to stresses and the fact that the material is moving by gravity down an inclined surface means that the material is being pulled off the forming structure due to the mass of the material which is already on the water slide. This creates tension stresses within the material, which stresses are locked into the material as it is cooled.